1. Field of the Invention
This invention relates to a printing apparatus having a feed mechanism.
2. Description of Related Art
Conventionally, a printing apparatus such as, e.g., an electrophotographic printer, a photocopier, and a facsimile machine, having a feed mechanism for feeding paper stacked on a paper feed tray formed outside into an interior of the printing apparatus generally employs a paper feed method to rotate a paper feed roller to feed the paper into the interior thereof as the paper stacked on the paper feed tray is pushed upward and pressed against the paper feed roller together with a paper feed stage on the paper feed tray using a motor and the like. The printing apparatus keeps the paper pressed against the paper feed roller even where printing operation is not performed, so that the paper can be fed successively to improve throughput. Keeping the paper pressed against the paper feed roller enables the printing apparatus to perform feed operation concurrently with commencement of printing operation. A printing apparatus having such a feed mechanism is described in Japanese Patent Publication No. Hei 9-263336.
With such a printing apparatus, it is necessary for a user to replace paper stacked on the paper feed tray, where a paper size transmitted together with image information from an information processing apparatus differs from an actual size of the paper stacked on the paper feed tray. In order to replace the paper, however, the user needs to remove the paper from the paper feed stage, and then the printing apparatus needs to detect non-existence of the paper on the paper feed stage, which is subsequently moved downward based on the detected result, since the paper on the paper feed tray and the paper feed stage are held in a manner to press the paper against the paper feed roller at that time.
However, there raises a problem that such the paper feed method takes a prolonged time to replace the paper because a timing of commencement of downward moving operation of the paper feed stage is after the printing apparatus detects non-existence of the paper on the paper feed stage after the user removes the paper on the paper feed stage.
This invention is made in consideration of the above described problem, and it is an object of this invention to provide a printing apparatus capable of replacing paper stacked on a paper feed tray easily and swiftly, even where a paper size transmitted together with image information from the an information processing apparatus differs from an actual size of the paper stacked on the paper feed tray.